You can hardly equate the effect of an approved delousing agent with that of a poison gas mixture used in a professional gas chamber that is intended to kill a person. Carbon monoxide already does the trick. Do you know how many people accidentally gas themselves every year because it started raining at their barbecue and they put the red-hot grill in the gazebo? They don't realize they're dying because they don't suffocate the usual way; the glowing coals don't smoke, but the embers burn the air and when you breathe that in, you just get pleasantly tired and simply fall asleep, while you suffocate from the oxygen levels in your blood dropping continuously. In fact, such a death is less painful and much gentler and perhaps also more humane than lethal injection, which is still used today in most countries with legal capital punishment. So you see, there would have been ways to make the whole story look at least halfway believable, but it just wasn't dramatic enough for the Jews, so they invented the horror stories of the gas chambers where they writhed to death by the millions, the women bent over their children to breathe their own breath into them so they could live a bit longer and whatnot, in gas chambers that were never found. What are still exhibited today as "gas chambers" in a bizarre "theme park" in Auschwitz and Bergen/Belsen are demonstrably delousing chambers. And yes, the delousing of the laundry was carried out with Zyklon B in the delousing trolleys, by personnel in protective clothing, and these trolleys were specially designed so that they were safe to use, of course. There have also been claims that the Jews were put in these wagons to kill them, but this claim is just as moronic as everything else in the whole story.